1. Field of the Invention
This invention relates to fiber optic transducers and, in particular, to a composite metal/optical fiber structure suitable for detecting either an electrical current or a magnetic field.
2. Description of the Prior Art
Sensor development is an area of considerable interest in non-telecommunication applications of fiber optic technology. For example, current sensing is being pursued with applications envisioned such as electrical power monitoring and industrial process control. To date, the research in current sensors has concentrated on single mode fiber sensors. These current sensors exploit the Faraday effect (polarization rotation proportional to a magnetic field) generated by a high current bus bar. The major problems with this approach are the small Verdet constant of high quality optical glass fiber, maintenance of low birefringence for long lengths and temperature stability. Due to the weak paramagnetic properties of glass, only high currents in the order of 5 to 800 Amps can be sensed by measurement of phase change. The use of single mode optical fibers in these sensors requires an interferometer configuration for phase change measurements.